I have used Flutter Blue for a college work, where I need to create an application to fetch and pass information to an equipment. The passing of this data must be automatic, as in any application (after all the end user should not look for the services and characteristics necessary to carry out the process). The problem is that I am not being able to perform the data passing soon after connecting with the device.
I'm using the App example I downloaded at https://github.com/pauldemarco/flutter_blue, so the basic idea is that as soon as I connect to my bluetooth device I send a message to a certain device. There is already an answered question that has the interest of setting notifications when connecting at Flutter Blue Setting Notifications
I followed the same example but instead of using _setNotification (c) I used the _writeCharacteristic (c), but it does not work.
_connect(BluetoothDevice d) async {
device = d;
// Connect to device
deviceConnection = _flutterBlue
.connect(device, timeout: const Duration(seconds: 4))
.listen(
null,
onDone: _disconnect,
);
// Update the connection state immediately
device.state.then((s) {
setState(() {
deviceState = s;
});
});
// Subscribe to connection changes
deviceStateSubscription = device.onStateChanged().listen((s) {
setState(() {
deviceState = s;
});
if (s == BluetoothDeviceState.connected) {
device.discoverServices().then((s) {
services = s;
for(BluetoothService service in services) {
for(BluetoothCharacteristic c in service.characteristics) {
if(c.uuid == new Guid("06d1e5e7-79ad-4a71-8faa-373789f7d93c")) {
_writeCharacteristic(c);
} else {
print("Nope");
}
}
}
setState(() {
services = s;
});
});
}
});
}
I have changed the original code so that it prints me the notifications as soon as I perform the writing method. The notifications should show me a standard message that is in the firmware of the device, but instead it is printing me the Local Name of the bluetooth chip, being that if I select the service and characteristic manually the return is the correct message.
You'd need to elaborate how you're executing writes on the descriptor - inside _writeCharacteristic(c).
BluetoothDescriptor.write() is a Future per docs, you should be able to catch any errors thrown during write.
Related
I am using service worker to achieve background sync functionality. Following is my code:
importScripts( 'https://storage.googleapis.com/workbox-cdn/releases/3.6.3/workbox-sw.js' )
const queue = new workbox.backgroundSync.Queue('registerQueue', { callbacks: {
queueDidReplay: function(requestArray) {
let requestSynced = 0
requestArray.forEach(item => {
if (!item.error) {
requestSynced++
}
})
if (requestSynced > 0) {
new BroadcastChannel('backgroundSynBroadCastChannel').postMessage(
requestSynced
)
}
} } }) const GraphQLMatch = /graphql(\S+)?/
self.addEventListener('fetch', event => { if (
null !== event.request.url.match(GraphQLMatch) &&
navigator.onLine === false ) {
const promiseChain = fetch(event.request.clone()).catch(err => {
return queue.addRequest(event.request)
})
event.waitUntil(promiseChain) } })
self.addEventListener('message', event => { if (!event.data) {
return }
switch (event.data) {
case 'skipWaiting':
self.skipWaiting()
break
default:
break } })
workbox.precaching.precacheAndRoute([])
/* * Alternate for navigateFallback & navigateFallbackBlacklist */ workbox.routing.registerNavigationRoute('/index.html', { blacklist: [/^\/__.*$/] })
On internet disconnect, the requests are queued on the indexed DB. But the problem is After acquiring the connection back, the background sync is made at least 5-10 mins later. Is there any way to do the background sync immediately upon internet re-connection or at least reduce the time for syncing.
Thanks in advance.
You could manually trigger a replay of a queue as soon as your connection is back by sending an event to the service worker.
In your service worker:
self.addEventListener('message', (event) => {
if (event.data.type === 'replayQueue') {
queue.replayRequests();
}
});
In your app (using workbox-window):
if ('serviceWorker' in navigator) this.wb = new Workbox('/service-worker.js');
window.addEventListener(‘online’, function(event){
this.wb.messageSW({type: 'replayQueue'});
});
Unfortunately, doesn't look like it's possible right now to change the timing for the sync. According to Google's Workbox documentation:
Browsers that support the BackgroundSync API will automatically replay
failed requests on your behalf at an interval managed by the browser,
likely using exponential backoff between replay attempts.
If Google's documentation is correct (at least for Chrome) that also means that the longer the user has been offline, the probability of a longer wait for the sync event increases.
#cyril-hanquez's idea is good as long as the user is still utilizing your site when they come back online. You might also want to add a "fetchDidFail" callback to handle more network outage edge cases. Along those lines: you might want to avoid relying on the status of "navigator.onLine", since it doesn't always do what one would expect.
I am have Xamarin Forms cross platform application for iOS, Android and UWP. I use the Xam.Plugin.Geolocator to get the location from each of the devices. My challenge with iOS is on the first launch of the app on a device. My code runs through and detects that IsGeolocationEnabled for the Plugin.Geolocator.Abstractions.IGeolocator object is false before the use is ever presented with the option to allow the application to use the device's location. This causes my app to inform the user that Location Services are not enabled for the application.
Basically I am hitting the line of code below before the use is ever asked about location services:
if (!App.gobj_RealGeoCoordinator.IsGeolocationEnabled)
ls_ErrorMessage = resourcestrings.GetValue("NoLocationServicesMessage");
On the other platforms, UWP at least, it seems that the app is paused while waiting for the user to respond to the request to use location services. Android just seems to automatically allow access to location if an app uses it.
Any idea how I can have the iOS detect if the request to use location services has been answered or not on the first run? Any suggestions would be greatly appreciated.
UPDATE(1):
I have all the correct items in my info.plist as seen below. I do eventually get the request to use the location just after my app has already checked IsGeolocationEnabled and decided the user has not enabled location services for the app.
UPDATE (2):
So I made a little progress using the following code.
try
{
while (!App.gobj_RealGeoCoordinator.IsGeolocationEnabled)
{
await Task.Delay(1000);
}
ViewModelObjects.AppSettings.CanAccessLocation = App.gobj_RealGeoCoordinator.IsGeolocationEnabled;
}
catch (Exception ex)
{
XXXXXXX
}
The challenge is that the plugin appears to provide me no way of knowing in the user has not responded to the location services dialog (i.e. IsGeolocationEnabled == false) versus the user said no to the location services dialog (also IsGeolocationEnabled == false). Any suggestions?
The way this type of permission request occurs on iOS is through an asynchronous dialog prompt, which is only shown if needed (and not until it is needed). Basically, you need to set up a callback from the CLLocation API. I have a helper class that I use for this purpose, which makes it even easier. Just call GetCurrentDeviceLocation() and pass it a callback function. The callback will only be invoked once the user has granted permission to the app, or if they previously granted permission:
public class GeoLocationService
{
readonly CLLocationManager _locationManager;
WeakReference<Action<Position>> _callback;
public GeoLocationService()
{
_locationManager = new CLLocationManager ();
_locationManager.AuthorizationChanged += AuthorizationChanged;
}
void AuthorizationChanged (object sender, CLAuthorizationChangedEventArgs e)
{
Action<Position> callback;
if (_callback == null || !_callback.TryGetTarget (out callback)) {
return;
}
if (IsAuthorized(e.Status)) {
var loc = _locationManager.Location;
var pos = new Position(loc.Coordinate.Latitude, loc.Coordinate.Longitude);
callback (pos);
}
}
static bool IsAuthorized(CLAuthorizationStatus status)
{
return
status == CLAuthorizationStatus.Authorized
|| status == CLAuthorizationStatus.AuthorizedAlways
|| status == CLAuthorizationStatus.AuthorizedWhenInUse;
}
public void GetCurrentDeviceLocation (Action<Position> callback)
{
_callback = new WeakReference<Action<Position>> (callback);
if (UIDevice.CurrentDevice.CheckSystemVersion (8, 0)) {
if (_locationManager.Location == null) {
_locationManager.RequestWhenInUseAuthorization ();
return;
}
}
AuthorizationChanged (null, new CLAuthorizationChangedEventArgs (CLAuthorizationStatus.Authorized));
}
}
I am looking to add offline support to a React Native application. The app currently runs off an API that is backed by a Postgres db.
I am already using NetInfo to determine whether a user has a connection or not but am looking to understand the best way to add offline capabilities where a user can continue to update their data and information and then just have everything sync when they get a connection again.
It seems like a pouchdb/couchdb solution is often recommended - however, I don't want to change my database at all. Ideally, I'd love to have some sort of way to store "jobs" of API calls in a queue and then execute them once connection is restored.
What is the best way to go about getting this offline functionality on a React Native App.
Thanks in advance!
You may use e.g. redux for data storage in general. Assuming you have a LOAD_POSTS_DATA action, which a component may fire at a point of time you may use a a reducer like this:
export const LOAD_POSTS_DATA = 'LOAD_POSTS_DATA';
var connected = ... // filled by NetInfo
const initialState = {
data: [],
};
export default function reducer(state = initialState, action) {
switch (action.type) {
case LOAD_POSTS_DATA:
if (connected) {
return {
open: true,
};
}
return state;
default:
return state;
}
}
export function load() {
return {
type: LOAD_POSTS_DATA,
};
}
This would only not load the data, for the deferring you would write a second reducer like this:
const CLEAR_QUEUE = 'CLEAR_QUEUE';
import { LOAD_POSTS_DATA } from './otherReducer';
var connected = ... // filled by NetInfo
const initialState = {
queue: [],
};
export default function reducer(state = initialState, action) {
switch (action.type) {
case LOAD_POSTS_DATA:
if (!connected) {
var q = state.queue;
q.push(action);
return {
queue: q,
};
}
return state;
case CLEAR_QUEUE:
return {
queue: []
}
default:
return state;
}
}
// needs to be called as soon as you go back only
// requires redux-thunk
export function getOperations() {
return (dispatch, getState) => {
const { thisReducer: { queue } } = getState();
queue.forEach(action => dispatch(action));
return {
type: CLEAR_QUEUE,
};
};
}
The second one stores every deferrable action (needs to be imported from other reducers) and uses redux-thunk to get hold of the actions and dispatch them as soon as you are back online.
Take a look at realm: https://realm.io, you can use it as database on your app, then as soon as you have the connectivity you can sync the data.
I have spent lot of time to find correct cordova plugin for parse push notifications for both Android & iOS platforms.
My requirements are:
To receive parse push notification (in both android & iOS)
Able to store all the incoming push notifications in mobile local storage Sqlite.
I have tried all the below parse push cordova plugins for both Android & iOS platforms.
https://github.com/avivais/phonegap-parse-plugin
https://github.com/taivo/parse-push-plugin
https://github.com/campers/parse-push-plugin
https://github.com/manishiitg/parse-push-plugin
For Android: All the above plugins are working perfectly to fulfill my above mentioned requirements.
For iOS: Only 1st plugin i.e https://github.com/avivais/phonegap-parse-plugin is working. And that too i was not able to save the notifications in local storage sqlite. That means only my 1st requirement is fulfilled but not my 2nd requirement.
All the github pages of remaining plugins (i.e 2nd, 3rd, 4th) states that:
"Please note that I've only worked on the Android aspect of this fork. The iOS side is not yet up to date."
Is there any plugin which will work for both Android & iOS platforms to fulfill my 2 requirements?
(or)
If there is no common plugin for both the platforms, then how can I store the incoming plugins in iOS sqlite?
Please help me. Thanks in advance.
I happen to maintain https://github.com/taivo/parse-push-plugin
It looks like you caught my fork at its infancy. I picked it up when the upstream fork seemed stagnant for a while and at that time I was only addressing the Android aspect. Since then I've provided full iOS support. And it works for parse-server as well as the out-going parse.com. I also did one better and made installation just a matter of
cordova add https://github.com/taivo/parse-push-plugin
and writing a few config.xml tags to indicate server url, and app id.
That should take out the big pain of manually messing with Android Manifest, Java, and Objective C when setting up the plugin.
It should now meet or exceed your requirement. To receive push notification and store in sqlite, all you have to do is set an event handler in javascript. Be sure to wrap it with some sort of device ready or platform ready event handler to ensure the plugin has properly loaded.
$ionicPlatform.ready(function(){
if(window.ParsePushPlugin){
ParsePushPlugin.on('receivePN', function(pn){
console.log('yo i got this notif:' + JSON.stringify(pn) );
//
// do your sqlite storage here
//
});
}
});
You just might be interested in the Azure Push Notifications. It combines both Push notification services so you can send messages to both devices from one central point.
I quote:
Notification Hubs A scalable, cross-platform solution for sending push
notifications to mobile devices, Notification Hubs works well with
Cordova apps. Notification Hubs manages the registrations with each
PNS. More important, Notification Hubs lets you create template
registrations so you can send messages to all registered devices,
regardless of platform, with only a single line of code. You can also
use tags to send targeted notifications only to devices with specific
registrations. For more information about Notification Hubs, see the
Azure Web site at aka.ms/nkn4n4.
Here i have a helper class for registering your device with the pushnotification service. For sending push notifications, you can use an azure portal and send styled push notifications in json format.
var Pushman = {
Initialize: function (hubConnString, hubName, gcmSenderId, callbackRegistered, callbackUnRegistered, callbackInlineNotification, callbackBackgroundNotification, callbackError) {
//store connection and callback information on app startup for Push Registration later
Pushman.HubConnectionString = hubConnString;
Pushman.HubName = hubName;
Pushman.GcmSenderId = gcmSenderId;
//callbacks
Pushman.RegisteredCallback = callbackRegistered;
Pushman.UnRegisteredCallback = callbackUnRegistered;
Pushman.NotificationForegroundCallback = callbackInlineNotification;
Pushman.NotificationBackgroundCallback = callbackBackgroundNotification;
Pushman.ErrorCallback = callbackError;
},
RegisterForPushNotifications: function (tags) {
//setup Azure Notification Hub registration
Pushman.Hub = new WindowsAzure.Messaging.NotificationHub(Pushman.HubName, Pushman.HubConnectionString, Pushman.GcmSenderId);
Pushman.Hub.registerApplicationAsync(tags).then(Pushman.onRegistered, Pushman.onError);
//setup PushPlugin registration
Pushman.Push = window.PushNotification;
var push;
//register depending on device being run
if (device.platform == 'android' || device.platform == 'Android' || device.platform == "amazon-fireos") {
//android
push = Pushman.Push.init(
{ "android": { "senderID": Pushman.GcmSenderId } }
);
push.on('registration', Pushman.onRegistered);
push.on('notification', Pushman.onAndroidNotification);
push.on('error', Pushman.onError);
} else {
//iOS
push = Pushman.Push.init(
{ "ios": { "alert": "true", "badge": "true", "sound": "true" } }
);
push.on('registration', Pushman.onRegistered);
push.on('notification', Pushman.onIOSNotification);
push.on('error', Pushman.onError);
}
},
UnRegisterForPushNotifications: function () {
if (Pushman.Hub != null) {
//dont pass through error handler
//unreg azure
Pushman.Hub.unregisterApplicationAsync()
.then(Pushman.onUnRegistered, null);
//unreg native
Pushman.Push.unregister(Pushman.onUnRegistered, null);
}
},
onRegistered: function (msg) {
Pushman.log("Registered: " + msg.registrationId);
//only call callback if registrationId actually set
if (msg.registrationId.length > 0 && Pushman.RegisteredCallback != null) {
Pushman.RegisteredCallback(msg);
}
},
onUnRegistered: function () {
Pushman.log("UnRegistered");
if (Pushman.UnRegisteredCallback != null) {
Pushman.UnRegisteredCallback();
}
},
onInlineNotification: function (msg) {
Pushman.log("OnInlineNotification: " + msg);
if (Pushman.NotificationForegroundCallback != null) {
Pushman.NotificationForegroundCallback(msg);
}
},
onBackgroundNotification: function (msg) {
Pushman.log("OnBackgroundNotification: " + msg);
if (Pushman.NotificationBackgroundCallback != null) {
Pushman.NotificationBackgroundCallback(msg);
}
},
onColdStartNotification: function (msg) {
Pushman.log("OnColdStartNotification: " + msg);
if (Pushman.NotificationBackgroundCallback != null) {
Pushman.NotificationBackgroundCallback(msg);
}
},
onError: function (error) {
Pushman.log("Error: " + error);
if (Pushman.ErrorCallback != null) {
Pushman.ErrorCallback(error);
}
},
onAndroidNotification: function (e) {
switch (e.event) {
case 'registered':
if (e.regid.length > 0) {
Pushman.onRegistered("Registered");
}
break;
case 'message':
if (e.foreground) {
//if this flag is set, this notification happened while app in foreground
Pushman.onInlineNotification(e.payload.message);
} else {
//otherwise app launched because the user touched a notification in the notification tray.
if (e.coldstart) {
//app was closed
Pushman.onColdStartNotification(e.payload.message);
}
else {
//app was minimized
Pushman.onBackgroundNotification(e.payload.message);
}
}
break;
case 'error':
Pushman.onError(e.msg);
break;
default:
Pushman.onError("Unknown message");
break;
}
},
onIOSNotification: function (event) {
//TODO: not sure how ios works re cold start vs inline msg types?
if (event.alert) {
navigator.notification.alert(event.alert);
}
if (event.badge) {
Push.setApplicationIconBadgeNumber(app.successHandler, app.errorHandler, event.badge);
}
},
tokenHandler: function (result) {
// iOS - not sure its use though appears somewhat important
// Your iOS push server needs to know the token before it can push to this device
// here is where you might want to send it the token for later use.
alert('device token = ' + result);
},
log: function (msg) {
console.log(msg);
},
}
///"class" variables - not sure how to put them into the js "class"
Pushman.Push = null;
Pushman.Hub = null;
Pushman.HubConnectionString = null;
Pushman.HubName = null;
Pushman.GcmSenderId = null;
Pushman.NotificationForegroundCallback = null;
Pushman.NotificationBackgroundCallback = null;
Pushman.RegisteredCallback = null;
Pushman.UnRegisteredCallback = null;
Pushman.ErrorCallback = null;
I did not write this myself, all credit goes to this guy.
Then you just need to initialize the plugin when the application starts:
//azure notificationshub connection information
notificationHubPath = "notificationhub name";
connectionString = "notificatin hub connectionstring";
//sender id for google cloud services
var senderIdGCM = "sender id from google gcm";
//tag registration (csv string), can be empty but not undefined
var registrationTagsCsv = ""; //test1, test2
var app = {
Initialize: function () {
//reg for onload event
this.AppStart();
},
AppStart: function () {
"use strict";
document.addEventListener('deviceready', app.onLoad, false);
document.addEventListener('deviceready', onDeviceReady.bind(this), false);
function onDeviceReady() {
// Handle the Cordova pause and resume events
document.addEventListener('pause', onPause.bind(this), false);
document.addEventListener('resume', onResume.bind(this), false);
// TODO: Cordova has been loaded. Perform any initialization that requires Cordova here.
};
function onPause() {
// TODO: This application has been suspended. Save application state here.
};
function onResume() {
// TODO: This application has been reactivated. Restore application state here.
};
},
onLoad: function () {
app.log("Initializing...");
//setup push notifications
Pushman.Initialize(connectionString, notificationHubPath, senderIdGCM,
app.onNotificationRegistered, app.onNotificationUnRegistered,
app.onNotificationInline, app.onNotificationBackground, app.onNotificationError);
//hookup cmd buttons
app.registerForPush();
//$("#register").click(app.registerForPush);
//$("#unregister").click(app.unRegisterForPush);
app.onAppReady();
},
registerForPush: function (a, c) {
app.log("Registering...");
//register for tags
Pushman.RegisterForPushNotifications(registrationTagsCsv);
},
unRegisterForPush: function (a, c) {
app.log("UnRegistering...");
//register for tags
Pushman.UnRegisterForPushNotifications();
},
onAppReady: function () {
app.log("Ready");
},
onNotificationRegistered: function (msg) {
app.log("Registered: " + msg.registrationId);
},
onNotificationUnRegistered: function () {
app.log("UnRegistered");
},
onNotificationInline: function (data) {
app.log("Inline Notification: " + data);
},
onNotificationBackground: function (data) {
app.log("Background Notification: " + data);
},
onNotificationError: function (error) {
app.log("Error: " + error);
},
log: function (msg) {
console.log(msg);
},
};
If you want to store the messages then you just need to add your code for storing to sql where the messages get received. You'll need an azure account to make this work, here you can get a free trail. It will allow you to send up to 1 million push notifications a month free of charge.
I think this article may be of use, it has more of a direct native workaround for your hybrid app to work
http://www.hiddentao.com/archives/2015/04/10/parse-push-notifications-for-your-android-and-ios-cordova-app/.
I'm working on a Cordova android app, and this seems to be a working solution
I want to store position coords (latitude, longitude) in a table in my MySQL DB querying a url in a way similar to this one: http://locationstore.com/postlocation.php?latitude=var1&longitude=var2 every ten seconds. PHP script works like a charm. Getting the coords in the device ain't no problem either. But making the request to the server is being a hard one. My code goes like this:
public class LocationHTTPSender extends Thread {
for (;;) {
try {
//fetch latest coordinates
coords = this.coords();
//reset url
this.url="http://locationstore.com/postlocation.php";
// create uri
uri = URI.create(this.url);
FireAndForgetDestination ffd = null;
ffd = (FireAndForgetDestination) DestinationFactory.getSenderDestination
("MyContext", uri);
if(ffd == null)
{
ffd = DestinationFactory.createFireAndForgetDestination
(new Context("MyContext"), uri);
}
ByteMessage myMsg = ffd.createByteMessage();
myMsg.setStringPayload("doesnt matter");
((HttpMessage) myMsg).setMethod(HttpMessage.POST);
((HttpMessage) myMsg).setQueryParam("latitude", coords[0]);
((HttpMessage) myMsg).setQueryParam("longitude", coords[1]);
((HttpMessage) myMsg).setQueryParam("user", "1");
int i = ffd.sendNoResponse(myMsg);
ffd.destroy();
System.out.println("Lets sleep for a while..");
Thread.sleep(10000);
System.out.println("woke up");
} catch (Exception e) {
// TODO Auto-generated catch block
System.out.println("Exception message: " + e.toString());
e.printStackTrace();
}
}
I haven't run this code to test it, but I would be suspicious of this call:
ffd.destroy();
According to the API docs:
Closes the destination. This method cancels all outstanding messages,
discards all responses to those messages (if any), suspends delivery
of all incoming messages, and blocks any future receipt of messages
for this Destination. This method also destroys any persistable
outbound and inbound queues. If Destination uses the Push API, this
method will unregister associated push subscriptions. This method
should be called only during the removal of an application.
So, if you're seeing the first request succeed (at least sometimes), and subsequent requests fail, I would try removing that call to destroy().
See the BlackBerry docs example for this here
Ok so I finally got it running cheerfully. The problem was with the transport selection; even though this example delivered WAP2 (among others) as an available transport in my device, running the network diagnostics tool showed only BIS as available. It also gave me the connection parameters that I needed to append at the end of the URL (;deviceside=false;ConnectionUID=GPMDSEU01;ConnectionType=mds-public). The code ended up like this:
for (;;) {
try {
coords.refreshCoordinates();
this.defaultUrl();
this.setUrl(stringFuncs.replaceAll(this.getUrl(), "%latitude%", coords.getLatitude() + ""));
this.setUrl(stringFuncs.replaceAll(this.getUrl(), "%longitude%", coords.getLongitude() + ""));
cd = cf.getConnection(this.getUrl());
if (cd != null) {
try {
HttpConnection hc = (HttpConnection)cd.getConnection();
final int i = hc.getResponseCode();
hc.close();
} catch (Exception e) {
}
}
//dormir
Thread.sleep(15000);
} catch (Exception e) {
} finally {
//cerrar conexiones
//poner objetos a null
}
Thanks for your help #Nate, it's been very much appreciated.